Microstructural correlations for specific surface area and triple phase boundary length for composite electrodes of solid oxide cells

The performances of Solid Oxide Cells (SOCs) are controlled by key microstructural properties such as the density of Triple Phase Boundary lengths (TPBl) and the interfacial specific surface areas (Si/j). These electrode properties are dependent on basic morphological parameters defined by the phase volume fractions and the Particle Size Distributions (PSD) of the percolated solid phases. The understanding of these relationships is of central importance for designing an optimum electrode microstructure. In this study, semi-analytical expressions for the density of TPBl and the interfacial specific surface areas are investigated. For this purpose, a large number of synthetic microstructures are generated by using validated models based on the sphere packing and the truncated Gaussian random field methods. The coefficients of the parametric equations for both investigated properties (TPBl density and Si/j) are fitted on the large database generated. The predictions of the microstructural correlations are in good agreement with the parameters directly computed on 3D reconstructions of typical LSCF-CGO and Ni-YSZ electrodes, thereby validating their reliability. •Microstructural correlations for specific surface area and triple phase boundary lengths.•Calibration of the semi-analytical relationships on a large dataset of synthetic microstructures.•Validation of the semi-analytical correlations on 3D reconstructions.